Abstract
Purpose: :
The development of neuroprotective therapies to reduce retinal ganglion cell (RGC) death in glaucoma is a research priority. Our aim was to determine whether retinal explant cultures could be used to screen novel neuroprotective strategies in order to identify candidate therapies with potential for clinical translation.
Methods: :
Retinal explants were cultured from adult rats (4 per retina) as described previously (Johnson et al IOVS 2008 49:3503-12). Explants were made 1 week following unilateral optic nerve crush (ONC; n=8) or laser-induced ocular hypertension (OHT; n=16), and from naïve rats (n=12 ONC controls; n=16 OHT controls). Explants from retinas contralateral to injury were also compared (n=8 contralateral to ONC; n=16 contralateral to OHT). Twenty-four hours after explantation, 1500 GFP+-mesenchymal stem cells (MSCs) were co-cultured on the vitreal surface of half of the explants in each group. RGC survival (mean±SEM per mm retina) was quantified 7 days later using NeuN immunohistochemical labelling. One-way ANOVA with Bonferroni post-hoc test was used to compare all groups.
Results: :
Quantification revealed that co-culture of retinal explants with MSCs significantly improved RGC survival, compared to untreated explants (127.36±8.33 cf. 58.14±1.99 RGC/mm, respectively; p<0.001). MSC neuroprotection was consistently observed regardless of whether RGCs were injured prior to explantation using either ONC (94.8±5.72 cf. 41.32±1.66 RGC/mm; p<0.001) or OHT (61.49±7.34 cf. 26.25±2.11 RGC/mm; p<0.001). In addition, explants from retinas contralateral to either ONC (50.79±2.59 RGC/mm) or OHT (15.32±3.27 RGC/mm) showed no difference in RGC loss compared to explants from naïve controls (58.14±1.99 RGC/mm for ONC, 21.66±3.51 RGC/mm for OHT; p>0.05). Co-culture with MSCs also reduced RGC death in explants from retinas contralateral to ONC (94.90±3.36 cf. 50.79±2.59 RGC/mm; p<0.001) and OHT (34.01±2.58 cf. 15.32±3.27 RGC/mm; p<0.05).
Conclusions: :
These data demonstrate that MSC-mediated RGC neuroprotection, as observed in vivo (see Johnson et al ARVO 2010), can be recapitulated in vitro using retinal explant cultures. Therefore, retinal explant cultures provide an accessible, controllable and efficient system in which to study new RGC neuroprotective strategies to identify potential therapies for translation.
Keywords: neuroprotection • retinal culture • ganglion cells